form and html-el:form Problems

I have a form with a drop-down menu in it. The drop-down menu is created using the <html-el:...> tag.

Everything displays well this way:

But, if I add this attribute; ENCTYPE="multipart/form-data", in the <html-el:form ...> tag like this:

I get this runtime error in the browser: Attribute ENCTYPE invalid for tag form according to TLD'

If I use the <form ENCTYPE="multipart/form-data" action="/content/AddFiles"> together with the <html-el:select ...>, <html-el ption ...>, <html-el ptions ...> tags, I do not get runtime error message; nonethess, the drop-down menu "cannot" be displayed.